Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The global population is estimated to number c.620,000-700,000 individuals (Wetlands International 2015). The European population is estimated at 25,100-50,100 pairs, which equates to 50,100-100,000 mature individuals (BirdLife International 2015). National population estimates include: c.1,000-10,000 individuals on migration and c.1,000-10,000 wintering individuals in China; c.50-1,000 individuals on migration and c.50-1,000 wintering individuals in Taiwan, China; c.50-1,000 individuals on migration and c.50-1,000 wintering individuals in Korea; c.1,000-10,000 individuals on migration and c.50-10,000 wintering individuals in Japan and c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in Russia (Brazil 2009).
The overall population trend is uncertain, as some populations are decreasing, while others are increasing, stable or have unknown trends (Wetlands International 2015). This species has had stable population trends over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007). Note, however, that these surveys cover less than 50% of the species's range in North America. The European population trend is unknown (BirdLife International 2015).
Behaviour This species is a full long-distance migrant that travels mainly via offshore and coastal routes using a number of favoured stopover sites (del Hoyo et al. 1996). It breeds from June to mid-July in solitary pairs (del Hoyo et al. 1996), departing the breeding grounds between mid-July and early-September (Hayman et al. 1986). The species usually occurs in small flocks on migration (Johnsgard 1981) although it may aggregate into larger flocks at stopover sites (Hayman et al. 1986), and in winter it forages in small to very large flocks (del Hoyo et al. 1996). Habitat Breeding The species breeds in the high Arctic on barren, stony tundra with well-drained ridges (Johnsgard 1981, del Hoyo et al. 1996), gentle slopes or level alluvial plains supporting scattered vegetation of willow Salix spp., Dryas spp. and saxifrage Saxifraga spp. usually less than 200 m above sea-level (Johnsgard 1981). Non-breeding On passage the species may occur on inland freshwater or saline lakes (del Hoyo et al. 1996) but it is largely coastal during the winter, inhabiting open sandy beaches exposed to the sea, the outer reaches of estuaries, rocky and muddy shores, mudflats (del Hoyo et al. 1996) and coral reefs (Urban et al. 1986). Diet Breeding When breeding the species takes insects (especially adult and larval Diptera, Coleoptera and Lepidoptera) as well as spiders and crustaceans (del Hoyo et al. 1996). On arrival on the breeding grounds the species may also complement its diet with plant matter (e.g. seeds, saxifrage buds, moss and algae) (del Hoyo et al. 1996) before invertebrate prey becomes available (Johnsgard 1981). Non-breeding During the winter its diet consists of small molluscs, crustaceans, polychaete worms and adult, larval and pupal insects (e.g. Diptera, Coleoptera, Lepidoptera, Hemiptera and Hymenoptera), as well as occasionally fish and carrion (del Hoyo et al. 1996). Breeding site The nest is a shallow depression on the bare earth (del Hoyo et al. 1996) of stony well-drained ridges, gentle slope or level alluvial plains (Johnsgard 1981).
The species is sensitive to disturbance on beaches (del Hoyo et al. 1996) (e.g. from recreational activities and free-running dogs (Thomas et al. 2003)), and is susceptible to avian influenza so may be threatened by future outbreaks of the virus (Melville and Shortridge 2006). In the Chinese, North Korean and South Korean regions of the Yellow Sea (East Asian flyway route) this species is threatened by the degradation and loss of wetland habitats through environmental pollution, reduced river flows and human disturbance (Kelin and Qiang 2006).
Conservation Actions Underway
The species is listed on Annex II of the Bern Convention.
Conservation Actions Proposed
The following information refers to the species's European range only: Recreation at staging and wintering areas needs to be controlled. Land reclamation, infrastructure development at key staging areas should be controlled.
Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J., Malpas, L.
BirdLife International (2019) Species factsheet: Calidris alba. Downloaded from http://www.birdlife.org on 18/06/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/06/2019.